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1. Rapid Recent Deforestation Incursion in a Vulnerable Indigenous Land in the Brazilian Amazon and Fire-Driven Emissions of Fine Particulate Aerosol Pollutants

   https://doi.org/10.3390/f11080829  

   de Oliveira, Gabriel ; Chen, Jing M. ; Mataveli, Guilherme A. ; Chaves, Michel E. ; Seixas, Hugo T. ; Cardozo, Francielle da ; Shimabukuro, Yosio E. ; He, Liming ; Stark, Scott C. ; dos Santos, Carlos A. ( August 2020 , Forests)

   null (Ed.)

   Deforestation in the Brazilian Amazon is related to the use of fire to remove natural vegetation and install crop cultures or pastures. In this study, we evaluated the relation between deforestation, land-use and land-cover (LULC) drivers and fire emissions in the Apyterewa Indigenous Land, Eastern Brazilian Amazon. In addition to the official Brazilian deforestation data, we used a geographic object-based image analysis (GEOBIA) approach to perform the LULC mapping in the Apyterewa Indigenous Land, and the Brazilian biomass burning emission model with fire radiative power (3BEM_FRP) to estimate emitted particulate matter with a diameter less than 2.5 µm (PM2.5), a primary human health risk. The GEOBIA approach showed a remarkable advancement of deforestation, agreeing with the official deforestation data, and, consequently, the conversion of primary forests to agriculture within the Apyterewa Indigenous Land in the past three years (200 km2), which is clearly associated with an increase in the PM2.5 emissions from fire. Between 2004 and 2016 the annual average emission of PM2.5 was estimated to be 3594 ton year−1, while the most recent interval of 2017–2019 had an average of 6258 ton year−1. This represented an increase of 58% in the annual average of PM2.5 associated with fires for the study period, contributing to respiratory health risks and the air quality crisis in Brazil in late 2019. These results expose an ongoing critical situation of intensifying forest degradation and potential forest collapse, including those due to a savannization forest-climate feedback, within “protected areas” in the Brazilian Amazon. To reverse this scenario, the implementation of sustainable agricultural practices and development of conservation policies to promote forest regrowth in degraded preserves are essential. 

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2. Forest policy and management approaches for carbon dioxide removal

   https://doi.org/10.1098/rsfs.2020.0001  

   vonHedemann, Nicolena ; Wurtzebach, Zachary ; Timberlake, Thomas J. ; Sinkular, Emily ; Schultz, Courtney A. ( October 2020 , Interface Focus)

   null (Ed.)

   Forests increasingly will be used for carbon dioxide removal (CDR) as a natural climate solution, and the implementation of forest-based CDR presents a complex public policy challenge. In this paper, our goal is to review a range of policy tools in place to support use of forests for CDR and demonstrate how concepts from the policy design literature can inform our understanding of this domain. We explore how the utilization of different policy tools shapes our ability to use forests to mitigate and adapt to climate change and consider the challenges of policy mixes and integration, taking a close look at three areas of international forest policy, including the Kyoto Protocol's Clean Development Mechanism, Reducing Emissions from Deforestation and Forest Degradation (REDD+) and voluntary carbon offset markets. As it is our expertise, we then examine in detail the case of the USA as a country that lacks aggressive implementation of national climate policies but has potential to increase CDR through reforestation and existing forest management on both public and private land. For forest-based CDR to succeed, a wide array of policy tools will have to be implemented in a variety of contexts with an eye towards overcoming the challenges of policy design with regard to uncertainty in policy outcomes, policy coherence around managing forests for carbon simultaneously with other goals and integration across governance contexts and levels. 

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3. Trade‐offs between carbon stocks and timber recovery in tropical forests are mediated by logging intensity

   https://doi.org/10.1111/gcb.14155  

   Roopsind, Anand ; Caughlin, T. Trevor ; van der Hout, Peter ; Arets, Eric ; Putz, Francis E. ( May 2018 , Global Change Biology)

   Forest degradation accounts for ~70% of total carbon losses from tropical forests. Substantial emissions are from selective logging, a land‐use activity that decreases forest carbon density. To maintain carbon values in selectively logged forests, climate change mitigation policies and government agencies promote the adoption of reduced‐impact logging (RIL) practices. However, whetherRILwill maintain both carbon and timber values in managed tropical forests over time remains uncertain. In this study, we quantify the recovery of timber stocks and aboveground carbon at an experimental site where forests were subjected to different intensities ofRIL(4, 8, and 16 trees/ha). Our census data span 20 years postlogging and 17 years after the liberation of future crop trees from competition in a tropical forest on the Guiana Shield, a globally important forest carbon reservoir. We model recovery of timber and carbon with a breakpoint regression that allowed us to capture elevated tree mortality immediately after logging. Recovery rates of timber and carbon were governed by the presence of residual trees (i.e., trees that persisted through the first harvest). The liberation treatment stimulated faster recovery of timber albeit at a carbon cost. Model results suggest a threshold logging intensity beyond which forests managed for timber and carbon derive few benefits fromRIL, with recruitment and residual growth not sufficient to offset losses. Inclusion of the breakpoint at which carbon and timber gains outpaced postlogging mortality led to high predictive accuracy, including out‐of‐sampleR²values >90%, and enabled inference on demographic changes postlogging. Our modeling framework is broadly applicable to studies that aim to quantify impacts of logging on forest recovery. Overall, we demonstrate that initial mortality drives variation in recovery rates, that the second harvest depends on old growth wood, and that timber intensification lowers carbon stocks.

    

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4. Land use strategies to mitigate climate change in carbon dense temperate forests

   https://doi.org/10.1073/pnas.1720064115  

   Law, Beverly E. ; Hudiburg, Tara W. ; Berner, Logan T. ; Kent, Jeffrey J. ; Buotte, Polly C. ; Harmon, Mark E. ( April 2018 , Proceedings of the National Academy of Sciences)

   Strategies to mitigate carbon dioxide emissions through forestry activities have been proposed, but ecosystem process-based integration of climate change, enhanced CO 2 , disturbance from fire, and management actions at regional scales are extremely limited. Here, we examine the relative merits of afforestation, reforestation, management changes, and harvest residue bioenergy use in the Pacific Northwest. This region represents some of the highest carbon density forests in the world, which can store carbon in trees for 800 y or more. Oregon’s net ecosystem carbon balance (NECB) was equivalent to 72% of total emissions in 2011–2015. By 2100, simulations show increased net carbon uptake with little change in wildfires. Reforestation, afforestation, lengthened harvest cycles on private lands, and restricting harvest on public lands increase NECB 56% by 2100, with the latter two actions contributing the most. Resultant cobenefits included water availability and biodiversity, primarily from increased forest area, age, and species diversity. Converting 127,000 ha of irrigated grass crops to native forests could decrease irrigation demand by 233 billion m 3 ⋅y −1 . Utilizing harvest residues for bioenergy production instead of leaving them in forests to decompose increased emissions in the short-term (50 y), reducing mitigation effectiveness. Increasing forest carbon on public lands reduced emissions compared with storage in wood products because the residence time is more than twice that of wood products. Hence, temperate forests with high carbon densities and lower vulnerability to mortality have substantial potential for reducing forest sector emissions. Our analysis framework provides a template for assessments in other temperate regions. 

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5. Sixteen hundred years of increasing tree cover prior to modern deforestation in Southern Amazon and Central Brazilian savannas

   https://doi.org/10.1111/gcb.15382  

   Wright, Jamie L. ; Bomfim, Barbara ; Wong, Corrine I. ; Marimon‐Júnior, Ben H. ; Marimon, Beatriz S. ; Silva, Lucas C. R. ( October 2020 , Global Change Biology)

   Tropical ecosystems are under increasing pressure from land‐use change and deforestation. Changes in tropical forest cover are expected to affect carbon and water cycling with important implications for climatic stability at global scales. A major roadblock for predicting how tropical deforestation affects climate is the lack of baseline conditions (i.e., prior to human disturbance) of forest–savanna dynamics. To address this limitation, we developed a long‐term analysis of forest and savanna distribution across the Amazon–Cerrado transition of central Brazil. We used soil organic carbon isotope ratios as a proxy for changes in woody vegetation cover over time in response to fluctuations in precipitation inferred from speleothem oxygen and strontium stable isotope records. Based on stable isotope signatures and radiocarbon activity of organic matter in soil profiles, we quantified the magnitude and direction of changes in forest and savanna ecosystem cover. Using changes in tree cover measured in 83 different locations for forests and savannas, we developed interpolation maps to assess the coherence of regional changes in vegetation. Our analysis reveals a broad pattern of woody vegetation expansion into savannas and densification within forests and savannas for at least the past ~1,600 years. The rates of vegetation change varied significantly among sampling locations possibly due to variation in local environmental factors that constrain primary productivity. The few instances in which tree cover declined (7.7% of all sampled profiles) were associated with savannas under dry conditions. Our results suggest a regional increase in moisture and expansion of woody vegetation prior to modern deforestation, which could help inform conservation and management efforts for climate change mitigation. We discuss the possible mechanisms driving forest expansion and densification of savannas directly (i.e., increasing precipitation) and indirectly (e.g., decreasing disturbance) and suggest future research directions that have the potential to improve climate and ecosystem models.

    

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